Flexible reaction cuvettes are known for carrying out reactions, such as PCR (polymerase chain reaction) amplification, followed by detection in a detection chamber. Such devices are disclosed, e.g., in EPA 381,501. In these devices, liquid reagents are pre-filled into burstable compartments connected via passageways to the detection chamber. The connections of the compartments to the passageways are given temporary seals which, until burst, prevent liquid from advancing to the chamber. Additionally, a PCR reaction compartment is provided into which a user injects patient liquid for testing. This compartment is also temporarily sealed in the same way, and temperature cycled to provide amplification of targeted DNA.
Bursting of the seals is preferably accomplished by processors having exterior pressure means, e.g. rollers, such as are shown in EPA 402,994. These are associated with heaters which can be used to heat the next compartment after an upstream one has been burst. Thereafter the pressure means are moved on to the now-heated next compartment to burst that one.
Although such reaction cuvettes and processors work well, there are occasions in which the color production is less than it should be. It has been discovered that this is due in part to the presence of air bubbles in the detection chamber which interfere with the necessary liquid reactions between the solutions transferred thereto and the detection sites of the chamber. It has further been found that such air bubbles come from upstream compartments which, because they have not been completely filled with liquid, have residual air that ends up being transferred to the detection chamber as the pressure rollers roll across the compartments to burst them. It is this air that can interfere with reaction in the detection chamber. Although one can envision correcting this by ensuring that reagent compartments are completely prefilled during manufacturing with liquid and no residual air, occasionally this does not happen and cuvettes having such residual air would have to be discarded, creating a waste of materials. Even in the absence of such failures, the exclusion of residual air does require a more complicated and therefore more expensive manufacturing process. But even if no reagent compartments fail to exclude all residual air, there is still a potential problem - the PCR reaction compartment is filled by the user, sealed and then heated. There has been no practical way of ensuring that that reaction compartment ends up with no residual air.
Accordingly, prior to this invention, there has been a need to process such cuvettes in such a way as to preclude residual air from the compartments from entering the detection chamber while liquid reactions have to take place.